The inventive concept relates to methods of manufacturing a solar cell and, more particularly, to methods of manufacturing a solar cell including a buffer layer formed by a vacuum deposition method.
A solar cell directly coverts sunlight into electrical energy. Solar cell techniques have been developed for a large area, low costs, and high efficiency of solar cells.
A thin film solar cell has an energy recovery period shorter than that of a silicon solar cell. Additionally, the thin film solar cell is easily thinned and widened. Thus, manufacturing costs of the thin film solar cell may be remarkably reduced by development of manufacturing techniques. Additionally, various researches have been conducted for CIS-based thin film solar cells using CIS-based thin films of copper-indium-gallium-selenium (Cu—In—Ga—Se) or copper-zinc-tin-selenium (Cu—Zn—Sn—Se) for increasing photoelectric transformation efficiency of the thin film solar cells.
Particularly, the Cu—In—Ga—Se (CIGS) thin film solar cell has photoelectric transformation efficiency greater than that of an amorphous silicon solar cell. Additionally, the CIGS thin film solar cell is stable without an initial deterioration phenomenon. Furthermore, the CIGS thin film solar cell has excellent properties, such that it may be substituted for a conventional single-crystalline silicon solar cell (20 W/kg) and may be developed as a light and high efficiency solar cell used in space. A power per a weight (e.g., about 100 W/kg) of the CIGS thin film solar cell is higher than those of a conventional silicon or GaAs solar cells (about 20 W/kg to about 40 W/kg). However, productivity of the CIGS thin film solar cell is relatively low. This is because there may not be techniques suitable for continuous production of the CIGS thin film solar cells and complex arrangement processing may be used in the production of the CIGS thin film solar cells. Recently, various researches have been conducted for increasing the productivity of the CIGS thin film solar cells.